1. Technical Field
The present invention relates generally to power systems; and more particularly to a system and method of operation for locating a disturbance in a power system based upon disturbance power and energy.
2. Related Art
The construction and operation of power systems has been generally known for years. However, with the relatively recent proliferation of sensitive electronic loads such as ASDs and microprocessors, the subject of power quality has recently received much interest. Efforts have been placed over the previous several years in an effort to characterize the overall level of power quality delivered to customers on various electric systems. Much work has also been done to develop systems that automatically identify the major types of power quality disturbances measured on distribution networks, such as capacitor switching, voltage sag, and impulsive transients.
Various types of commercial loads, such as semiconductor processing plants, have enhanced requirements for clean, continuous power. When the power is interrupted for any reason, the work within the plants may also be interrupted, oftentimes causing damage to ongoing processes. Thus, utility companies are often held to an agreed upon level of performance with respect to such loads. If a disturbance occurs, the utility company may recompense the customer for damages caused. Further, in the near future, parties responsible for disturbances may be penalized for causing interruptions in the power supply that result in customer downtime. However, presently, disturbances cannot be easily located. Resultantly, liability relating to caused disturbances is difficult to assign.
Thus, there is a need in the art for locating disturbances within power systems in a reliable manner so that liability for causing the disturbances may be assigned.
Thus, in order to overcome the shortcomings of the prior systems, among other shortcomings, a disturbance locating system constructed according to the present invention is deployed within a power grid to estimate a relative direction to a disturbance in a power system. The system includes a voltage transducer, a current transducer and disturbance energy determination circuitry. The system may also include disturbance power determination circuitry.
The voltage transducer couples to an output of a voltage transformer, the output of the voltage transformer representative of a voltage on a line within the power grid. The current transducer couples to an output of a current transformer, the output of the current transformer representative of the current flowing through the line, the output having a forward reference direction and a behind reference direction. According to one embodiment, the voltage and current transformers are hard wired to the line. However, in another embodiment, the voltage and current transformers need not require physical coupling to the line to produce outputs representative of the state of the line.
The disturbance energy determination circuitry couples to the voltage transducer and the current transducer. Based upon the inputs received, the disturbance energy determination circuitry determines disturbance energy flowing in the line and estimates a relative direction to a source of the disturbance as either in front of or behind of the disturbance locating system. The disturbance energy determination circuitry may include disturbance power determination circuitry that couples to the voltage transducer and the current transducer. In such case, the disturbance power is provided to the disturbance energy determination circuitry for estimating the relative direction to the disturbance.
A method for determining a relative direction to a source of a disturbance according to the present invention may be performed in conjunction with the disturbance locating system. The method includes as a first step monitoring a current flowing through, and a voltage on the line in the power grid at the location. Next, the method includes determining a steady state power flow through the line and a transient power flow through the line during a disturbance condition. Based upon the steady state power flow and the transient power flow through the line, the method includes determining a disturbance power flow through the line. Then, based upon the disturbance power flow through the line, method includes determining a relative direction to the source of the disturbance. The method may also include determining a disturbance energy flow through the line and determining the relative direction to the source of the disturbance is also based upon the disturbance energy flow through the line.
Moreover, other aspects of the present invention will become apparent with further reference to the drawings and specification which follow.